> Parents want one setting that says "this is a child" and then expect online platforms to respond appropriately.

This law does not do that. It breaks the age of children into several buckets so that platforms, websites, and advertisers can target specific demographics. They won't "respond appropriately" they'll just use this data point as another way to improve how they exploit children online. Now every pedo with a website can tell how old the kid is so they can better adjust their grooming for that age bracket.